This invention relates to an improved composition for lubrication and a process for making that composition. The composition and process of this invention produce improved lubricating results with less ecological and safety dangers than current lubricants.
The primary purpose of lubrication is the separation of moving surfaces to minimize friction and wear. Several distinct regimes are commonly used to describe the fundamental principles of lubrication. These range from complete separation by a fluid lubricant, through partial separation in boundry lubrication, to dry sliding where solid material properties and surface chemistry dominate. Application of basic considerations often enable an optimum match of machine design and material selection with lubricant and method of lubrication.
Machines of all types require lubrication. The quality of the lubrication provided greatly affects the efficiency, service life and other aspects of performance of the machine. Of particular importance in this regard are machining operations, such as cutting, milling and drilling, where lubricants/coolants are essential to the machining operations. The lubricating requirements involving new high strength, high toughness metal alloys can be particularly demanding. Thus, increasing technical demands are being placed upon lubricants.
At the very same time, ecological and safety concerns are also demanding the use of safer, more biodegradable compositions than the heavily petroleum based and toxic compositions of the past. Therefore there remains unanswered needs for environmentally friendly and health safe compositions that yield lubricating qualities which meet today""s demanding specifications.
As noted, one of the most demanding applications for lubricants today is in precision machining of high strength, high toughness alloys. In these machining applications, in general, there are five attributes that are measured when considering lubricant performance:
(1) The lubricant composition lubricates the cutting edge/chip/workpiece interfaces so that chips will slide over the cutting tool surfaces with minimum friction thereby generating minimal frictional heat and cutting tool wear. It must also prevent build-up at the cutting edges and extend tool life.
(2) The lubricant composition must conduct heat away from the operation.
(3) The lubricant composition must be able to penetrate the interfaces.
(4) The lubricant composition must not be corrosive to the surfaces of the work, the machine or the tools.
(5) The lubricant composition must be able to carry away loose chips from the cutting edges.
In satisfying the foregoing requirements in demanding applications a good lubricant will extend machine and tool service life while producing excellent work.
Many prior lubricants have been based on a refined petroleum base stock. U.S. Pat. No. 4,203,854 discusses a lubricant based on a mixture of refined petroleum and molybdenum disulfide with other additives. U.S. Pat. No. 5,792,728 discusses a composition comprising molybdenum disulfide, soap flakes and polytetrafluoroethylene. Each of the foregoing two patents are incorporated herein by reference in their entirety.
It is thus an object of the invention to disclose a lubricant composition, and a process for creating that composition, which satisfy all of the foregoing qualities, even in the most demanding applications, yet is also more environmentally friendly and safe to use than similar prior lubricants.
It should be further noted that, although much of the foregoing discussion relates to machining operations, the lubricant composition of this invention can also be used in other applications such as lubricating gasoline and diesel engines and other similar lubrication operations.
This invention is therefore directed to a composition, and process for creating said composition, for use in various lubrication applications. The foregoing objectives can be accomplished with a lubricant composition comprising:
(1) Molybdenum disulfide particles with a mass mean size of less than about 1 micron; preferably less than about 0.9 microns and most preferably from about 0.1 to 0.6 microns; and
(2) lubricating base oil(s), preferably selected from the group consisting of soybean oil, canola oil, other vegetable oils and mixtures of the foregoing;
wherein the molybdenum disulfide particles are suspended within the lubricating base oil(s). The lubricant composition may also comprise other performance additives.
The lubricant composition is prepared by adding the molybdenum disulfide particles to the lubricating base oil(s) with sufficient high shear mixing to suspend the molybdenum disulfide particles in the lubricating base oil(s). Preferably the high shear mixing is performed in the presence of a magnetic field.